Substrate treating apparatus

ABSTRACT

A substrate treating apparatus for treating substrates with a treating liquid includes a treating tank having an inner tank for storing the treating liquid, and an outer tank for collecting the treating liquid overflowing the inner tank. A supply pipe interconnects the inner tank and the outer tank for circulating the treating liquid. A first branch pipe is shunted from the supply pipe, and a separator is mounted on the first branch pipe for separating deionized water and a solvent in the treating liquid, and discharging the deionized water. A second branch pipe interconnects positions upstream and downstream of the separator, and a deionized water remover is mounted on the second branch pipe for adsorbing and removing deionized water from the treating liquid. An injection pipe is connected to the supply pipe for injecting deionized water in a position downstream of the separator. A solvent injector injects the solvent into the injection pipe. A controller carries out a deionized water cleaning process for supplying deionized water from the injection pipe and cleaning the substrates inside the cleaning tank with deionized water, then a replacing process for injecting the solvent from the solvent injector and replacing the deionized water with the solvent, a separating and removing process for switching to the first branch pipe and causing the separator to remove the deionized water from the treating liquid, and an adsorbing and removing process for switching to the second branch pipe and causing the deionized water remover to adsorb and remove the deionized water from the treating liquid.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

This invention relates to substrate treating apparatus for treating,e.g. cleaning, substrates such as semiconductor wafers or glasssubstrates for liquid crystal displays (hereinafter called simplysubstrates) with a treating liquid.

(2) Description of the Related Art

Conventionally, this type of apparatus includes, for example, a treatingtank for storing a treating liquid and receiving substrates, and anozzle for supplying isopropyl alcohol (IPA) gas to a space above thetreating tank (see Japanese Unexamined Patent Publication H10-22257, forexample). With this apparatus, after supplying deionized water to thetreating tank and cleaning substrates, IPA gas is supplied to the spaceabove the treating tank to form an IPA atmosphere therein. By pulling upand moving the substrates in the IPA atmosphere, the deionized wateradhering to the substrates is replaced with IPA to promote drying of thesubstrates.

The conventional apparatus with such construction has the followingdrawback.

The conventional apparatus can promote drying of the substrates to somedegree by pulling up the substrates cleaned with deionized water out ofthe deionized water, and moving the substrates in the IPA atmosphere.However, deionized water adhering to fine patterns formed on thesubstrates cannot be dried sufficiently, and thus a possibility ofunsatisfactory drying performance.

In the latest semiconductor devices in the field of memory, capacitorsconstructed in a cylindrical shape have begun to be employed as atechnique for drastically increasing the degree of integration. Such acylindrical structure has a very high aspect ratio, and it isparticularly difficult to dry sufficiently deionized water havingentered gaps of that structure. Thus, the above drawback is notablehere. A similar problem can occur also with devices related to what isknown as MEMS (Micro Electro Mechanical Systems).

It is conceivable to pull up substrates after replacing deionized waterwith a solvent before pulling up the substrates, instead of usingdeionized water as final treating liquid. In this case, however,although it is important to replace the deionized water with the solventsufficiently, the concentration of deionized water in the solvent cannotbe reduced below a certain level even if a large quantity of solvent ismixed into the deionized water. The solvent cannot replace the deionizedwater sufficiently. Thus, there still is a possibility of unsatisfactorydrying performance due to the deionized water.

When pulling up the substrates after replacing the deionized water withthe solvent as noted above, even if a large quantity of solvent is mixedinto the deionized water, the deionized water having entered finestructures of the substrates gradually mixes into the treating liquid,resulting in a phenomenon of the deionized water concentration graduallyincreasing in the treating liquid. Thus, there still is a possibility ofunsatisfactory drying performance due to the deionized water. Inaddition, when the substrates are pulled up, the fine structures couldcollapse due to the surface tension of the deionized water.

A conventional apparatus of this type may include a plurality oftreating tanks, and a transport mechanism for transporting substratesfrom one treating tank to another.

The apparatus successively treats the substrates in different treatingtanks with different treating liquids or solutions (see JapaneseUnexamined Patent Publication H10-22257, for example). Such apparatusperforms a series of treatments while moving the substrates successivelysuch that, for example, the substrates have surfaces lightly etched withBHF (buffered hydrofluoric acid) in the first treating tank, and cleanedwith deionized water in the second treating tank. The deionized water isreplaced with IPA (isopropyl alcohol) in the third treating tank, andthe substrates are dried in a solvent vapor atmosphere in the fourthtreating tank.

The conventional apparatus with such construction has the followingdrawback.

With the substrates having fine patterns formed thereon, the finepatterns could collapse when the substrates are moved from one treatingtank to another, due to the surface tension of deionized water remainingin the patterns.

SUMMARY OF THE INVENTION

This invention has been made having regard to the state of the art notedabove, and its object is to provide a substrate treating apparatus freefrom unsatisfactory drying of substrates due to deionized water, whichis achieved by minimizing deionized water concentration in a solvent.

Another object of the invention is to provide a substrate treatingapparatus free from unsatisfactory drying of substrates and collapse offine structures, which is achieved by minimizing deionized water in atreating liquid replaced with a solvent.

It is a further object of the invention to provide a substrate treatingapparatus free from collapse of fine patterns formed on substrates,which is achieved by increasing a rate of removing deionized water.

The above object is fulfilled, according to this invention, by asubstrate treating apparatus for treating substrates with a treatingliquid, comprising a treating tank having an inner tank for storing thetreating liquid, and an outer tank for collecting the treating liquidoverflowing the inner tank; a supply pipe interconnecting the inner tankand the outer tank for circulating the treating liquid; a first branchpipe shunted from the supply pipe; a separating device mounted on thefirst branch pipe for separating deionized water and a solvent in thetreating liquid, and discharging the deionized water; a second branchpipe interconnecting positions upstream and downstream of the separatingdevice; a deionized water removing device mounted on the second branchpipe for adsorbing and removing deionized water from the treatingliquid; an injection pipe connected to the supply pipe for injectingdeionized water in a position downstream of the separating device; asolvent injecting device for injecting the solvent into the injectionpipe; and a control device for carrying out a deionized water cleaningprocess for supplying deionized water from the injection pipe andcleaning the substrates inside the cleaning tank with the deionizedwater, then a replacing process for injecting the solvent from thesolvent injecting device and replacing the deionized water with thesolvent, a separating and removing process for switching to the firstbranch pipe and causing the separating device to remove the deionizedwater from the treating liquid, and an adsorbing and removing processfor switching to the second branch pipe and causing the deionized waterremoving device to adsorb and remove the deionized water from thetreating liquid.

According to this invention, the control device first carries out adeionized water cleaning process for supplying deionized water from theinjection pipe and cleaning the substrates inside the cleaning tank withthe deionized water, and then a replacing process for injecting thesolvent from the solvent injecting device and replacing the deionizedwater with the solvent. Although the replacing process can replace alarge part of deionized water with the solvent, the concentration ofdeionized water in the treating liquid cannot be reduced below a certainlevel. Then, the control device switches the flow of the treating liquidto the first branch pipe for the separating and removing process toremove the deionized water from the treating liquid with the separatingdevice, and then switches the flow of the treating liquid to the secondbranch pipe for the adsorbing and removing process by the deionizedwater removing device. Consequently, the deionized water removing devicecan adsorb and remove only the deionized water mixed in the solvent. Inthis way, the deionized water concentration in the solvent is reduced toa minimal level. This prevents an unsatisfactory drying of thesubstrates due to the deionized water in the solvent.

The above adsorbing and removing device may be a molecular sieve,activated carbon or alumina, for example.

The apparatus according to this invention may further comprise a mixermounted on the first branch pipe for mixing deionized water and solvent;and a third branch pipe interconnecting a position upstream of themixer, and a position downstream of the mixer and upstream of theseparating device; wherein the control device is arranged, when thesolvent is water-soluble, to switch a flow of the treating liquid to thethird branch pipe to carry out the separating and removing process, andwhen the solvent is water-insoluble, to allow the treating liquid toflow through the mixer to carry out the separating and removing process.

The separating device has a characteristic of tending to separatedeionized water and solvent in a well mixed state better than when thedeionized water and solvent are completely separated. Then, when thesolvent is water-insoluble, the control device switches the flow of thetreating liquid from the third branch pipe to the second branch pipe tocarry out the mixing process for causing the mixer to mix the solventand deionized water before the separating and removing process. Thus,the deionized water in the solvent is efficiently separated.Particularly where the solvent is water-insoluble such as a fluoricsolvent, the deionized water and solvent do not mix easily. The mixingstep by the mixer can improve the separating efficiency of theseparating device.

In this invention, the separating device may have a filter forseparating oil and water, a housing enclosing the filter, an inflowportion formed in the housing for introducing the treating liquid, anoutflow portion formed in the housing for letting out the treatingliquid having passed through the filter, a discharge portion formed inthe housing for discharging deionized water separated by the filter, anda cooling device for cooling the filter.

Since solubility of deionized water in the solvent can be made the lowerat the lower temperature, the separating efficiency of the deionizedwater and solvent is improved by cooling action of the cooling device.

In another aspect of the invention, a substrate treating apparatus fortreating substrates with a treating liquid, comprises a treating tankhaving an inner tank for storing the treating liquid, and an outer tankfor collecting the treating liquid overflowing the inner tank; a supplypipe interconnecting the inner tank and the outer tank for circulatingthe treating liquid; a deionized water supply device for supplyingdeionized water as treating liquid; a solvent supply device forsupplying a solvent as treating liquid; a branch pipe shunted from thesupply pipe; a deionized water removing device mounted on the branchpipe for removing deionized water from the treating liquid; a solventinjecting device for injecting the solvent into the supply pipedownstream of the deionized water removing device; and a control devicefor carrying out a deionized water cleaning process for supplyingdeionized water from the deionized water supply device and cleaning thesubstrates inside the cleaning tank with the deionized water, then areplacing process for injecting the solvent from the solvent supplydevice and replacing the deionized water with the solvent, a deionizedwater removing process for switching to the branch pipe and causing thedeionized water removing device to remove the deionized water from thetreating liquid, and causing the solvent injecting device to replenishthe solvent.

According to this invention, the control device first carries out adeionized water cleaning process for supplying deionized water from thedeionized water supply device and cleaning the substrates inside thecleaning tank with the deionized water, and then a replacing process forsupplying the solvent from the solvent supply device and replacing thedeionized water with the solvent. Thereafter, the control device carriesout the deionized water removing process by switching to the branchpipe, and causing the deionized water removing device to removedeionized water from the treating liquid. Thus, insufficient drying andcollapse of the fine structures can be prevented by removing thedeionized water in the treating liquid replaced with the solvent as muchas possible. Not only the deionized water in the treating liquid but acertain amount of solvent also is removed through the deionized waterremoving process, thereby decreasing the solvent. However, the solventinjecting device replenishes the solvent to compensate for the loss inquantity of the solvent accompanying the deionized water removal.

The apparatus according to the invention may further comprise a firstmixer mounted on the branch pipe upstream of the deionized waterremoving device for mixing fluids; a deionized water injecting devicefor injecting deionized water into the branch pipe upstream of the firstmixer; and a second mixer mounted on the supply pipe downstream of thesolvent injecting device for mixing fluids; wherein the control deviceis arranged, when deionized water concentration in the treating liquidfalls below a predetermined value, to inject deionized water from thedeionized water injecting device, and control the deionized waterinjecting device and the solvent injecting device such that a sum of aninjection rate of the solvent from the solvent injecting device and adifference between an injection rate of deionized water and a quantityof the treating liquid removed by the deionized water removing devicebecomes substantially zero.

When the deionized water concentration in the treating liquid fallsbelow a predetermined value, the deionized water removing efficiency ofthe deionized water removing device will lower. Thus, the control deviceinjects deionized water from the deionized water injecting device tomaintain the deionized water removal efficiency as if with a nosemedicine. At this time, the solvent concentration in the treating liquidmay be kept constant by making substantially zero the sum of theinjection rate of the solvent from the solvent injecting device, and thedifference between the injection rate of deionized water and thequantity of the treating liquid (solvent and deionized water) removed bythe deionized water removing device.

In a further aspect of the invention, a substrate treating apparatus fortreating substrates with a treating liquid, comprises a treating tankfor storing the treating liquid; a supply pipe for circulating thetreating liquid to supply the treating liquid discharged from thetreating tank back to the treating tank; a first branch pipe shuntedfrom the supply pipe; a cooling device mounted on the first branch pipefor cooling the treating liquid flowing therethrough; a second branchpipe interconnecting positions of the supply pipe upstream anddownstream of the cooling device; a separating device mounted on thesecond branch pipe for separating deionized water and a solvent in thetreating liquid, and discharging the deionized water from the treatingliquid; an injection pipe connected to the supply pipe for injectingdeionized water in a position downstream of the separating device; awater-soluble solvent injecting device for injecting a water-solublesolvent into the injection pipe; a water-insoluble solvent injectingdevice for injecting a water-insoluble solvent into the injection pipe;and a control device for carrying out a deionized water cleaning processfor cleaning the substrates inside the cleaning tank with deionizedwater, then a replacing process for injecting the water-soluble solventfrom the water-soluble solvent injecting device into the supply pipe andreplacing the deionized water with the water-soluble solvent, a coolingprocess by switching a channel to the first branch pipe for the coolingdevice to cool the treating liquid, a separating and removing process byswitching a channel to the second branch pipe for the separating deviceto remove the deionized water from the treating liquid, and areplacement promoting process for injecting the water-insoluble solventfrom the water-insoluble solvent injecting device into the supply pipe.

According to this invention, the control device carries out thedeionized water cleaning process for cleaning the substrates in thetreating tank with deionized water by supplying deionized water from thefilling pipe to the supply pipe. This process removes chemicals,contaminants and the like from the substrates with deionized water.Next, the control device carries out the replacing process for injectingthe water-soluble solvent from the water-soluble solvent injectingdevice into the supply pipe, and replacing the deionized water with thewater-soluble solvent. After replacing the deionized water stored in thetreating tank with the water-soluble solvent, the control device carriesout the cooling process by switching the channel to the first branchpipe for the cooling device to cool the treating liquid. Subsequently,the control device carries out the separating and removing process byswitching the channel to the second branch pipe for the separatingdevice to remove deionized water from the treating liquid. Deionizedwater can be removed efficiently from the treating liquid since thetreating liquid has been cooled in the cooling process to render thedeionized water not readily dissolvable in the water-soluble solvent.Then, the replacement promoting process is performed by injecting thewater-insoluble solvent from the water-insoluble solvent injectingdevice. The water-soluble solvent and deionized water are replaceablenearly completely with the water-insoluble solvent since thewater-soluble solvent and deionized water are made not readilydissolvable in the water-insoluble solvent in the preceding coolingprocess. Thus, the deionized water in the treating tank can be removedefficiently to prevent the deionized water from remaining in the finepatterns formed on the substrates. As a result, this apparatus canprevent collapse of the fine patterns formed on the substrates.

The apparatus in this invention may further comprise a third branch pipeinterconnecting positions upstream and downstream of the separatingdevice; and a deionized water removing device mounted on the thirdbranch pipe for adsorbing and removing the deionized water from thetreating liquid; wherein the control device is arranged to switch thechannel to the third branch pipe after the separating and removingprocess.

An increased removal rate is achieved by operating the deionized waterremoving device to adsorb and remove the deionized water remainingwithout being removed through the separating and removing process.

BRIEF DESCRIPTION OF THE DRAWINGS

For the purpose of illustrating the invention, there are shown in thedrawings several forms which are presently preferred, it beingunderstood, however, that the invention is not limited to the precisearrangement and instrumentalities shown.

FIG. 1 is a block diagram showing an outline of a substrate treatingapparatus in Embodiment 1;

FIG. 2 is a view in vertical section showing an outline of a staticmixer;

FIG. 3 is a view in vertical section showing an outline of an oil-waterseparation filter;

FIG. 4 is a graph showing deionized water concentration in a treatingliquid and rate of damage to substrates;

FIG. 5 is a flow chart of operation;

FIG. 6 is a block diagram showing an outline of a substrate treatingapparatus in Embodiment 2;

FIG. 7 is a view in vertical section showing an outline of a staticmixer;

FIG. 8 is a view in vertical section showing an outline of an oil-waterseparation filter;

FIG. 9 is a flow chart of operation;

FIG. 10 is a block diagram showing an outline of a substrate treatingapparatus in Embodiment 3;

FIG. 11 is a view in vertical section showing an outline of a staticmixer;

FIG. 12 is a view in vertical section showing an outline of an oil-waterseparation filter; and

FIG. 13 is a flow chart of operation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of this invention will be described in detail hereinafterwith reference to the drawings.

Embodiment 1

FIG. 1 is a block diagram showing an outline of a substrate treatingapparatus in Embodiment 1.

A treating tank 1 includes an inner tank 3 and an outer tank 5. Theinner tank 3 stores a treating liquid or solution, and can receivewafers W held by a holding arm 7. The holding arm 7 includes supportelements arranged on lower positions of an arm portion for contactinglower edges of the wafers W and supporting the wafers W in upstandingposture. The holding arm 7 is vertically movable between a treatingposition inside the inner tank 3 and a standby position above the innertank 3. The inner tank 3 stores deionized water, solvents or a mixturethereof as a treating liquid or solution, and the treating liquidoverflowing the inner tank 3 is collected in the outer tank 5surrounding an upper portion of the inner tank 3. The inner tank 3 hastwo jet pipes 9 disposed at opposite sides in the bottom thereof forsupplying the treating liquid into the inner tank 3.

The jet pipes 9 are connected to one end of a supply pipe 11 having theother end connected to a drain port 13 formed in the outer tank 5. Thesupply pipe 11 has a three-way valve 15, a pump 17, a three-way valve 19and an in-line heater 21 arranged in order from upstream, i.e. adjacentthe outer tank 5. The three-way valve 15 is switchable betweencirculation and drain of the treating liquid. The pump 17 circulates thetreating liquid, and the three-way valve 19 is switchable betweencirculation of the treating liquid and removal of deionized water (to bedescribed in detail hereinafter). The in-line heater 21 heats thetreating liquid circulating through the supply pipe 11 to apredetermined temperature.

The supply pipe 11 has one end of an injection pipe 23 connected to aposition thereof downstream of the in-line heater 21 and upstream of thejet pipes 9. The other end of the injection pipe 23 is connected to adeionized water source 25. The injection pipe 23 has a control valve 27,a mixing valve 29 and a flow control valve 31 arranged in order fromdownstream to upstream. The control valve 27 controls supply and cutoffof deionized water, solvents or a treating solution of solvents indeionized water. The mixing valve 29 has, connected thereto, one end ofeach of two chemical pipes 33 and 35, with the other ends thereofconnected to an HFE source 37 and an IPA source 39, respectively. Thetwo chemical pipes 33 and 35 have flow control valves 41 and 43 foradjusting flow rate, respectively. The mixing valve 29 has a function tomix one or both of HFE (hydrofluoroether), which is a water-insolublefluoric solvent, and water-soluble IPA (isopropyl alcohol) intodeionized water.

The mixing valve 29 corresponds to the solvent injecting device in thisinvention.

The inner tank 3 has a batting 45 disposed at the bottom thereof. Thebatting 45 has a vibrator 47 with an ultrasonic transducer attached tothe bottom surface thereof. The batting 45 is filled with deionizedwater of a quantity that soaks a lower part of the inner tank 3. Thevibrator 47 applies ultrasonic vibration to the treating liquid in theinner tank 3 through the deionized water of the batting 45.

The above vibrator 47 corresponds to the ultrasonic vibration applyingdevice in this invention.

The supply pipe 11 has a first branch pipe 49 shunted therefrom. Thefirst branch pipe 49 has an oil-water separation filter 51 forseparating the deionized water and solvent in the treating liquid. Thesupply pipe 11 further includes a second branch pipe 53 extendingparallel to the first branch pipe 49. The second branch pipe 53communicates with the first branch pipe 49 in positions upstream anddownstream of the oil-water separation filter 51. The second branch pipe53 has an adsorption filter 55 for adsorbing and removing deionizedwater from the treating liquid.

The adsorption filter 55 is formed of a molecular sieve, activatedcarbon, alumina or the like, and has a function to adsorb and removeeven a trace quantity of deionized water from the treating liquid.

The first branch pipe 49 noted above has a static mixer 57 disposedupstream of the oil-water separation filter 51. A third branch pipe 58communicates with the first branch pipe 49 in positions upstream of thisstatic mixer 57, and downstream of the static mixer 57 and upstream ofthe oil-water separation filter 51. The third branch pipe 58 includes acontrol valve 59 for controlling circulation therethrough. The staticmixer 57 has an injection portion 60 disposed in an upstream positionthereof for injecting deionized water into the treating liquidcirculating through the first branch pipe 49, and a flow control valve61 for controlling a flow rate of deionized water to the injectionportion 60. As described in detail hereinafter, the static mixer 57 hasno actuator, but agitates and mixes fluids by action of division,turning and reversal.

A control valve 63 is disposed between the three-way valve 19 and firstbranch pipe 49, and a control valve 65 is disposed between the controlvalve 63 and second branch pipe 53. The first branch pipe 49 has acontrol valve 67 disposed in the most upstream position thereof, and acontrol valve 69 in the most downstream position. The second branch pipe53 has a control valve 71 disposed downstream of the adsorption filter55.

The oil-water separation filter 51 corresponds to the separating devicein this invention. The adsorption filter 55 corresponds to the deionizedwater removing device in this invention. The static mixer 57 correspondsto the mixer in this invention.

Next, reference is made to FIG. 2 which is a view in vertical sectionshowing an outline of the static mixer 57.

The static mixer 57 includes a body portion 73 and a plurality ofelements 75 arranged in the body portion 73. Each element 75 is in theform of a rectangular plate member twisted 180 degrees. Adjoiningelements 75 are twisted in opposite directions. The static mixer 57 hasthe above-noted injection portion 60 disposed in the upstream positionthereof for injecting deionized water into the treating liquid, andagitates and mixes these liquids by action of division, turning andreversal. Particularly where the solvent is water-insoluble such as HFE(hydrofluoroether) that does not dissolve completely in deionized water,the deionized water can be separated efficiently by passing the mixturethrough the oil-water separation filter 51 after mixing deionized waterand solvent in the static mixer 57.

Next, reference is made to FIG. 3 which is a view in vertical sectionshowing an outline of the oil-water separation filter 51.

The oil-water separation filter 51 includes a housing 77, a liquidintroducing portion 79 in the bottom of the housing 77, a filter 81 forfiltering the treating liquid from the liquid introducing portion 79, afirst storage portion 83 for storing part having a high specific gravityof the liquid having passed the filter 81, a second storage portion 85for storing part having a low specific gravity, an inflow portion 87through which the treating liquid flows into the liquid introducingportion 79, a first discharge portion 89 for discharging the liquid fromthe first storage portion 83, a second discharge portion 91 fordischarging the liquid from the second storage portion 85, and a coolingpipe 93 arranged along the outer wall of housing 77 for indirectlycooling the filter 81. The inflow portion 87 is located upstream withrespect to the first branch pipe 49, and the first discharge portion 89downstream with respect to the first branch pipe 49. The filter 81 is amicrofiber filter having a function to trap a differentiated free liquidand flocculate the liquid into coarse masses. The free liquiddifferentiated to the order of microns is flocculated to the order ofmillimeters, thereby to be instantaneously distributed into a perfectbilayer system by specific gravity difference.

The above first discharge portion 89 corresponds to the outflow portionin this invention. The second discharge portion 91 corresponds to thedischarge portion in this invention. The cooling pipe 93 corresponds tothe cooling device in this invention.

The inner tank 3 has a concentration meter 95 disposed in an upperposition thereof for measuring a deionized water concentration in thetreating liquid. The concentration meter 95 may be the infraredabsorption type, for example.

A controller 97, which corresponds to the control device in thisinvention, performs an overall control of the apparatus including thevertical movement of the holding arm 7, operation and stopping of thepump 17, temperature control of the in-line heater 21, flow control ofthe flow control valves 31, 41 and 43, opening and closing of thecontrol valve 27, switching control of the three-way valves 15 and 19,vibration control of the vibrator 47, opening and closing of the controlvalves 59, 63, 65, 67, 69 and 71, and flow control of the flow controlvalve 61.

The controller 97 controls the various components noted above to carryout a “deionized water cleaning process” for moving the holding arm 7 tothe treating position and supplying deionized water as treating liquid,a “replacing process” for supplying a solvent (HFE or IPA) to thetreating liquid to replace the deionized water with the solvent, and a“separating and removing process” for causing the oil-water separationfilter 51 to remove deionized water from the treating liquid. When thedeionized water concentration in the solvent falls to or below a firstpredetermined value, the controller 97 carries out an “adsorbing andremoving process” for causing the adsorption filter 55 to adsorb andremove deionized water from the treating liquid (which will be describedin detail hereinafter). Only when the deionized water concentration inthe treating liquid (solvent) falls to or below a second predeterminedvalue, the controller 97 operates the vibrator 47 to apply ultrasonicvibration, to replace the deionized water having entered the finestructures of wafers W with the solvent. However, where the solvent iswater-insoluble and does not easily dissolve in deionized water (e.g.HFE), the “separating and removing process” is carried out by passingthe treating liquid through the oil-water separation filter 51 afteroperating the static mixer 57 to agitate and mix the deionized water andsolvent by action of division, turning and reversal, thereby improvingthe efficiency of separation by the oil-water separation filter 51.

For the first predetermined value noted above, it is preferable toconfirm the saturation solubility of the solvent in the treating liquid,but the concentration meter 95 can be used as substitution. A specificvalue of the first predetermined value is 0.1 [%] or less, for example.When the adsorbing and removing process is carried out while thedeionized water concentration is still high, the adsorption filter 55will lose water-adsorbing power in a short time, necessitating frequentchanges of the adsorption filter 55. The first predetermined value isset in order to avoid such an inconvenience.

The second predetermined value noted above corresponds to the solventconcentration in the treating liquid (a liquid mixture of deionizedwater and solvent) being 10,000 [ppm], for example. Inventors hereinconducted an experiment in which wafers W with fine structures formed onsurfaces thereof were immersed in a treating liquid in the inner tank 3,ultrasonic vibration was applied thereto while changing theconcentration of the solvent (HFE or IPA) in the treating liquid, anddamage to the fine structures on the wafers W was checked. The resultsare shown in FIG. 4. FIG. 4 is a graph showing deionized waterconcentration in the treating solution and rate of damage to thesubstrates. The experimental conditions at that time were that L&S (line& space) of the fine structures formed on the wafers W were 80 nm/150nm, and the structures were formed of polysilicon. The ultrasonicvibration was 40 [W], 42 kHz and 5 [min].

Based on the results of the above experiment, Inventors have found thatdamage to the fine structures on the wafers W is within a permissibleextent when the concentration of the solvent (HFE or IPA) in thetreating liquid is 10,000 [ppm] or less. Thus, it is desirable that, inthe above-noted series of processes including “deionized water cleaningprocess”, ultrasonic vibration is applied only when the solventconcentration falls to or below the above-noted second predeterminedvalue. This allows the solvent to replace also the deionized waterhaving entered the fine structures on the wafers W, and besides theprocess can be carried out with little possibility of damage to the finestructures on the wafers W.

Next, operation of the above substrate treating apparatus will bedescribed with reference to FIG. 5. FIG. 5 is a flow chart of operation.

Step S1

The controller 97 switches the three-way valve 15 to a position forallowing circulation, switches the three-way valve 19 to a position forcommunication with the supply pipe 11, opens the control valve 27, andadjusts the flow control valve 31 to supply deionized water in apredetermined flow rate from the deionized water source 25 through theinjection pipe 23 and supply pipe 11 to the inner tank 3. After fillingthe inner tank 3, outer tank 5 and supply pipe 11 with deionized water,the controller 97 operates the pump 17 and in-line heater 21 to heat thedeionized water to a predetermined temperature (e.g. 60° C.). After thepredetermined temperature is reached, the controller 97 lowers theholding arm 7 from the standby position to the treating position, andmaintains the holding arm 7 in the treating position for a predeterminedtime. As a result, the wafers W are cleaned with the deionized waterheated to the predetermined temperature.

Step S2

The controller 97 stops the in-line heater 21 and pump 17, switches thethree-way valve 15 to a drain position, and closes the flow controlvalve 31. The controller 97 adjusts the flow control valve 41 to apredetermined flow rate to supply HFE to the supply pipe 11. After theinner tank 3 and outer tank 5 are filled with HFE, the controller 97switches the three-way valve 15 to the position for communication withthe supply pipe 11, and operates the pump 17. As a result, a large partof deionized water in the treating liquid is discharged, and HFE ismixed into the treating liquid whereby the deionized water is replacedwith the solvent.

Step S3

The controller 97 opens the control valves 63, 67 and 69, and switchesthe three-way valve 19 to a position for communication with the firstbranch pipe 49. As a result, the treating liquid passes through theoil-water separation filter 51 after water-insoluble HFE and deionizedwater are fully mixed by the static mixer 57.

At this time, the flow control valve 61 may be adjusted to injectdeionized water into the treating liquid flowing through the staticmixer 57. A deionized water concentration in the solvent below a certainvalue would lower the efficiency of the oil-water separation filter 51separating deionized water and solvent. Deionized water is positivelyinjected and mixed into the treating liquid having a reduced deionizedwater concentration, so that the oil-water separation filter 51 mayseparate deionized water below the certain value as drawn out by theinjected deionized water.

Step S4

After executing above step S3 for a predetermined time, the controller97 opens the control valve 59 to switch the channel to the third branchpipe 58, providing a bypass for the treating liquid to circumvent thestatic mixer 57. As a result, the treating liquid with a reduceddeionized water concentration passes only through the oil-waterseparation filter 51.

The above step S4 may be skipped, and only step S3 may be executed.

Step S5

The controller 97 branches the process according to whether thedeionized water concentration from the concentration meter 95 has thefirst predetermined value or less. Specifically, when the deionizedwater concentration exceeds the first predetermined value, step S4 isrepeated. Otherwise, the operation proceeds to step S6.

Steps S6 and S7

The controller 97 opens the control valve 65, and closes the controlvalves 67 and 69. As a result, the treating liquid (largely HFE) withthe deionized water concentration at the first predetermined value orless flows into the second branch pipe 53. A small quantity of deionizedwater remaining in the treating liquid is adsorbed and removed by theadsorption filter 55. The controller 97 continues the process of step S6until the deionized water concentration falls to the secondpredetermined value or less. The operation moves to step S8 when thedeionized water concentration falls to the second predetermined value orless.

Step S8

The controller 97 drives the vibrator 47 to apply ultrasonic vibrationat a predetermined output to the treating liquid in the inner tank 3 fora predetermined time. As a result, the deionized water having enteredthe fine structures on the wafers W can be replaced with the treatingliquid, i.e. HFE. Since the deionized water concentration in thetreating liquid has been reduced to a minimal level, no damage is doneto the fine structures on the wafers W.

According to this embodiment, as described above, the controller 97first carries out the deionized water cleaning process for cleaningwafers W with deionized water, then the replacing process for injectingHFE and replacing the deionized water with HFE. The controller 97switches the flow of the treating liquid to the first branch pipe 49 forthe separating and removing process to remove the deionized water fromthe treating liquid with the oil-water separation filter 51, and thenswitches the flow of the treating liquid to the second branch pipe 53for the adsorbing process by the adsorption filter 55. Consequently, theadsorption filter 55 can adsorb and remove only a trace quantity ofdeionized water remaining unremoved by the separating and removingprocess. In this way, the deionized water concentration in HFE isreduced to a minimal level. This prevents an unsatisfactory drying ofthe wafers W due to the deionized water in HFE.

The deionized water having entered the fine structures formed on thewafers W is not easily replaceable with HFE. The deionized water in thefine structures can be replaced with HFE by applying ultrasonicvibration from the vibrator 47. If the deionized water concentration inHFE is high, the fine structures on the wafers W may be damaged. Such aninconvenience is avoided by applying ultrasonic wave after the deionizedwater concentration in HFE falls to the predetermined value or less.This achieves improved yield.

This invention is not limited to the foregoing embodiment, but may bemodified as follows:

(1) The foregoing embodiment provides the static mixer 57 for fullymixing the water-insoluble solvent with deionized water prior to passagethrough the oil-water separation filter 51. Where a water-solublesolvent is used, there is no need for the static mixer 57. Thissimplifies the apparatus construction.

(2) The foregoing embodiment provides the vibrator 47 attached to theinner tank 3. This component may be omitted where no ultrasonicvibration is applied. This simplifies the apparatus construction.

(3) The foregoing embodiment uses, by way of example, fluoric HFE aswater-insoluble solvent, and IPA as water-soluble solvent. Thisinvention is applicable to other solvents. It is possible to use, forexample, HFC (hydrofluorocarbon) as fluoric solvent other than HFE.

(4) The foregoing embodiment provides the concentration meter 95 mountedin the inner tank 3 for measuring deionized water concentration. Thisconstruction may be modified to measure deionized water concentration inthe treating liquid circulating through the supply pipe 11.

Embodiment 2

FIG. 6 is a block diagram showing an outline of a substrate treatingapparatus in Embodiment 2.

A treating tank 1 includes an inner tank 3 and an outer tank 5. Theinner tank 3 stores a treating liquid or solution, and can receivewafers W held by a holding arm 7. The holding arm 7 includes supportelements arranged on lower positions of an arm portion for contactinglower edges of the wafers W and supporting the wafers W in upstandingposture. The holding arm 7 is vertically movable between a “treatingposition” inside the inner tank 3 and a “standby position” above theinner tank 3. The inner tank 3 stores deionized water, solvents or amixture thereof as a treating liquid or solution, and the treatingliquid overflowing the inner tank 3 is collected in the outer tank 5surrounding an upper portion of the inner tank 3. The inner tank 3 hastwo jet pipes 9 disposed at opposite sides in the bottom thereof forsupplying the treating liquid into the inner tank 3.

The jet pipes 9 are connected to one end of a supply pipe 11 having theother end connected to a drain port 13 formed in the outer tank 5. Thesupply pipe 11 has a three-way valve 15, a pump 17, a three-way valve19, a static mixer 101 and an in-line heater 102 arranged in order fromupstream, i.e. adjacent the outer tank 5. The three-way valve 15 isswitchable between circulation and drain of the treating liquid. Thepump 17 circulates the treating liquid, and the three-way valve 19 isswitchable between circulation of the treating liquid and removal ofdeionized water (to be described in detail hereinafter). The in-lineheater 102 heats the treating liquid circulating through the supply pipe11 to a predetermined temperature.

The supply pipe 11 has a branch pipe 103 shunted therefrom at thethree-way valve 19. The first branch pipe 103 has an oil-waterseparation filter 104 for separating the deionized water and solvent inthe treating solution.

The oil-water separation filter 104 corresponds to the deionized waterremoving device in this invention.

The branch pipe 103 noted above has a static mixer 105 disposed upstreamof the oil-water separation filter 104. The static mixer 105 has aninjection portion 106 disposed in an upstream position thereof forinjecting deionized water into the treating liquid circulating throughthe branch pipe 103, and a flow control valve 107 for controlling a flowrate of deionized water to the injection portion 106. A flowmeter 108 isdisposed upstream of the flow control valve 107 for measuring the flowrate of deionized water. As described in detail hereinafter, the staticmixer 105 has no actuator, but agitates and mixes fluids by action ofdivision, turning and reversal. A control valve 109 is disposed betweenthe three-way valve 19 and branch pipe 103. The branch pipe 103 has acontrol valve 110 disposed in the most downstream position.

The static mixer 105 corresponds to the first mixer in this invention.The static mixer 101 corresponds to the second mixer in this invention.The injection portion 106 corresponds to the deionized water injectingdevice in this invention.

The static mixer 101, as does the static mixer 105 described above, hasan injection portion 111 disposed in an upstream position thereof forinjecting IPA (isopropyl alcohol) into the treating liquid circulatingthrough the supply pipe 11. The injection portion 111 has a flow controlvalve 112 for controlling an injection flow rate. A flowmeter 113 isdisposed upstream of the flow control valve 112 for measuring the flowrate of IPA from the IPA source.

The above injection portion 111 corresponds to the solvent injectingdevice in this invention.

A deionized water source 114, an HFE source 115 and an IPA source 116are provided for supplying deionized water, HFE (hydrofluoroether) andIPA (isopropyl alcohol) to the outer tank 5. The deionized water source114 supplies deionized water to the outer tank 5 through a supply pipe117. Its flow rate is controlled by a flow control valve 118 mounted onthe supply pipe 117. The HFE source 115 supplies HFE to the outer tank 5through a supply pipe 119. Its flow rate is controlled by a flow controlvalve 120 mounted on the supply-pipe 119. The IPA source 116 suppliesIPA to the outer tank 5 through a supply pipe 121. Its flow rate iscontrolled by a flow control valve 122 mounted on the supply pipe 121.

The deionized water source 114 and supply pipe 117 correspond to thedeionized water supply device in this invention. The HFE source 115, IPAsource 116 and supply pipes 119 and 121 correspond to the solvent supplydevice in this invention.

Next, reference is made to FIG. 7 which is a view in vertical sectionshowing an outline of the static mixers 101 and 105 which are identicalin construction.

The static mixer 101 (105) includes a cylindrical body portion 123 and aplurality of elements 124 arranged in the body portion 123. Each element124 is in the form of a rectangular plate member twisted 180 degrees.Adjoining elements 124 are twisted in opposite directions. The staticmixer 101 (105) has the above-noted injection portion 111 (106) disposedin the upstream position thereof for injecting IPA (deionized water)into the treating liquid, and agitates and mixes these liquids by actionof division, turning and reversal. Particularly where the solvent iswater-insoluble such as HFE (hydrofluoroether) that does not dissolvecompletely in deionized water, deionized water can be separatedefficiently by passing the mixture through the oil-water separationfilter 104 after mixing deionized water and solvent in the static mixer105.

Next, reference is made to FIG. 8 which is a view in vertical sectionshowing an outline of the oil-water separation filter 104.

The oil-water separation filter 104 includes a housing 125, a liquidintroducing portion 126 in the bottom of the housing 125, a filter 127for filtering the treating liquid from the liquid introducing portion126, a first storage portion 128 for storing part having a high specificgravity of the liquid having passed through the filter 127, a secondstorage portion 129 for storing part having a low specific gravity, aninflow portion 130 through which the treating liquid flows into theliquid introducing portion 126, a first discharge portion 131 fordischarging the liquid from the first storage portion 128, a seconddischarge portion 132 for discharging the liquid from the second storageportion 129, and a cooling pipe 133 arranged along the outer wall ofhousing 125 for indirectly cooling the filter 127. The inflow portion130 is located upstream with respect to the branch pipe 103, and thefirst discharge portion 131 downstream with respect to the branch pipe103. The filter 127 is a microfiber filter having a function to trap adifferentiated free liquid and flocculate the liquid into coarse masses.The free liquid differentiated to the order of microns is flocculated tothe order of millimeters, thereby to be instantaneously distributed intoa perfect bilayer system by specific gravity difference. The seconddischarge portion 132 has a flowmeter 134 attached thereto for measuringa discharge flow rate.

By circulating a coolant through the above cooling pipe 133, thedeionized water and solvent can separated with increased efficiency.This is because solubility of the deionized water in the solvent is madethe lower at the lower temperature.

The above first discharge portion 131 corresponds to the outflow portionin this invention. The second discharge portion 132 corresponds to thedischarge portion in this invention. The cooling pipe 133 corresponds tothe cooling device in this invention.

The inner tank 3 has a concentration meter 135 disposed in an upperposition thereof for measuring a deionized water concentration in thetreating liquid. The concentration meter 135 may be the infraredabsorption type, for example.

A controller 136, which corresponds to the control device in thisinvention, performs an overall control of the apparatus including thevertical movement of the holding arm 7, operation and stopping of thepump 17, temperature control of the in-line heater 102, flow control ofthe flow control valves 107, 112, 118, 120 and 122, opening and closingof the control valves 109 and 110, and switching control of thethree-way valves 15 and 19. The flow rates measured by the flowmeters108, 113 and 134 are inputted to the controller 136.

The controller 136 controls the various components noted above to carryout a “deionized water cleaning process” by moving the holding arm 7 tothe treating position and supplying deionized water as treating liquid,and a “replacing process” by supplying a solvent (HFE or IPA) to thetreating liquid to replace the deionized water with the solvent. Thecontroller 136 carries out also a “deionized water removing process” forcausing the oil-water separation filter 104 to remove deionized waterfrom the treating liquid (to be described in detail hereinafter). Onlywhen the deionized water concentration in the treating liquid (solvent)falls to or below a predetermined value, the controller 136 carries outa solvent replenishing operation. Where the solvent is water-insoluble(e.g. HFE) and does not easily dissolve in deionized water, the“deionized water removing process” is carried out by passing thetreating liquid through the oil-water separation filter 104 afteroperating the static mixer 105 to agitate and mix the deionized waterand solvent by action of division, turning and reversal, therebyimproving the efficiency of separation by the oil-water separationfilter 104.

The predetermined value noted above corresponds to the solventconcentration in the treating liquid (a liquid mixture of deionizedwater and solvent) being 10,000 [ppm], for example.

Next, operation of the above substrate treating apparatus will bedescribed with reference to FIG. 9. FIG. 9 is a flow chart of operation.

Step S11

The controller 136 switches the three-way valve 15 to a position forallowing circulation, switches the three-way valve 19 to a position forcommunication with the supply pipe 11, and adjusts the flow controlvalve 118 to supply deionized water in a predetermined flow rate fromthe deionized water source 114 to the outer tank 5. After filling theinner tank 3, outer tank 5 and supply pipe 11 with deionized water, thecontroller 136 operates the pump 17 and in-line heater 102 to heat thedeionized water to a predetermined temperature (e.g. 60° C.). After thepredetermined temperature is reached, the controller 136 lowers theholding arm 7 from the standby position to the treating position,maintains the holding arm 7 in the treating position for a predeterminedtime. As a result, the wafers W are cleaned with the deionized waterheated to the predetermined temperature.

Step S12

The controller 136 stops the pump 17, switches the three-way valve 15 toa drain position, and closes the flow control valve 118. The controller136 adjusts the flow control valve 120 to supply HFE in a predeterminedflow rate to the outer tank 5. After the inner tank 3 and outer tank 5are filled with HFE, the controller 136 switches the three-way valve 15to the position for communication with the supply pipe 11, and operatesthe pump 17. As a result, a large part of deionized water in thetreating liquid is discharged, and HFE is mixed into the treatingsolution whereby the deionized water is replaced with the solvent. Next,the controller 136 closes the flow control valve 120, and opens the flowcontrol valve 122 to supply IPA to the outer tank 5, thereby forming atreating liquid including HFE and IPA.

Step S13

The controller 136 switches the three-way valve 19 to a position forcommunication with the branch pipe 103. As a result, the treating liquidpasses through the oil-water separation filter 104 after HFE/IPA anddeionized water are fully mixed by the static mixer 105. Thus, thedeionized water is separated from the treating liquid largely made up ofHFE/IPA, and is discharged from the second discharge portion 132.

At this time, the flow control valve 107 may be adjusted to injectdeionized water into the treating liquid flowing through the staticmixer 105. A deionized water concentration in the treating liquid belowa certain value would lower the efficiency of the oil-water separationfilter 104 separating deionized water and solvent. Deionized water ispositively injected and mixed into the treating liquid having a reduceddeionized water concentration, so that the oil-water separation filter104 may separate deionized water below the certain value as drawn out bythe injected deionized water. The oil-water separation filter 104, whenremoving the deionized water, will remove a certain amount ofwater-soluble IPA along with the deionized water.

Step S14

With start of the above deionized water removing process, the controller136 receives one output signal after another from the concentrationmeter 135 to determine a deionized water concentration in the treatingliquid. Step S13 is repeated until the deionized water concentration inthe treating liquid becomes 1,000 ppm or less, for example. That is,deionized water removal is carried out until the deionized water becomesa predetermined concentration. The deionized water having entered thefine structures on the wafers W gradually joins the treating liquid,causing a temporary phenomenon of the deionized water concentrationincreasing gradually.

Step S15

When the deionized water concentration in the treating liquid fallsbelow a predetermined value, the deionized water removing efficiency ofthe oil-water separation filter 104 will lower. Thus, the controller 136adjusts the flow control valve 107 to inject deionized water through theinjection portion 106 to maintain the deionized water removal efficiencyas if with a nose medicine. At this time, the solvent concentration inthe treating liquid may be kept constant by making substantially zerothe sum of the injection rate II of the solvent through the injectionportion 111, and the difference between the injection rate DI ofdeionized water outputted from the flowmeter 108 and quantity EX of thetreating liquid (solvent and deionized water) removed by the oil-waterseparation filter 104.

Step S16

The controller 136 checks passage of time with a timer not shown, andrepeats step S15 until elapse of a predetermined time. This processallows the solvent to replace fully the deionized water oozing from thefine structures on the wafers W.

Through the above series of processes, the wafers W are cleaned withdeionized water, and the deionized water is fully replaced with thesolvents (HFE/IPA). Subsequently, the holding arm 7 is pulled up to thestandby position to finish the cleaning treatment of the wafers W.

As described above, the controller 136 carries out the replacing processfor supplying HFE/IPA to replace deionized water with the solvents afterthe deionized water cleaning process. Then, the controller 136 carriesout the deionized water removing process by switching to the branch pipe103, and causing the oil-water separation filter 104 to remove deionizedwater from the treating liquid. Thus, insufficient drying and collapseof the fine structures can be prevented by removing the deionized waterin the treating liquid replaced with HFE/IPA as much as possible. Notonly the deionized water in the treating liquid but a certain amount ofIPA also is removed through the deionized water removing process,thereby decreasing the treating liquid including HFE/IPA. However, IPAis replenished through the injection portion 106 to compensate for theloss in quantity of the solvent accompanying the deionized waterremoval.

This invention is not limited to the foregoing embodiment, but may bemodified as follows:

(1) The foregoing embodiment provides the static mixers 101 and 116 forfully mixing the solvents with deionized water. Where a water-solublesolvent is a main component, the static mixers 101 and 116 may beomitted. This simplifies the apparatus construction.

(2) The foregoing embodiment provides the oil-water separation filter104 as deionized water removing device. Instead, a deionized wateradsorbing device (adsorption filter) may be employed which is formed ofa molecular sieve, activated carbon, alumina or the like for adsorbingand removing even a trace quantity of deionized water from the treatingliquid. The oil-water separation filter 104 and deionized wateradsorbing device may be arranged in parallel and to be switchable foruse. This construction can use the characteristic of each to removedeionized water efficiently.

(3) The foregoing embodiment uses, by way of example, fluoric HFE aswater-insoluble solvent, and IPA as water-soluble solvent. Thisinvention is applicable to other solvents. It is possible to use, forexample, HFC (hydrofluorocarbon) as fluoric solvent other than HFE.

(4) The foregoing embodiment provides the concentration meter 135mounted in the inner tank 3 for measuring deionized water concentration.This construction may be modified to measure deionized waterconcentration in the treating liquid circulating through the supply pipe11.

(5) The foregoing embodiment employs the construction for supplyingdeionized water and solvents to the outer tank 5. Instead, for example,deionized water and solvents may be supplied directly into the supplypipe 11.

Embodiment 3

FIG. 10 is a block diagram showing an outline of a substrate treatingapparatus in Embodiment 3.

The substrate treating apparatus in this embodiment includes a treatingtank 1. The treating tank 1 includes an inner tank 3 and an outer tank5. The inner tank 3 stores a treating liquid or solution, and canreceive wafers W held by a holding arm 7. The holding arm 7 includessupport elements arranged on lower positions of an arm portion forcontacting lower edges of the wafers W and supporting the wafers W inupstanding posture. The holding arm 7 is vertically movable between a“treating position” inside the inner tank 3 and a “standby position”above the inner tank 3. The inner tank 3 stores deionized water,solvents or a mixture thereof as a treating liquid or solution, and thetreating liquid overflowing the inner tank 3 is collected in the outertank 5 surrounding an upper portion of the inner tank 3. The inner tank3 has two jet pipes 9 disposed at opposite sides in the bottom thereoffor supplying the treating liquid into the inner tank 3.

The jet pipes 9 are connected to one end of a supply pipe 11 having theother end connected to a drain port 13 formed in the outer tank 5. Thesupply pipe 11 has a three-way valve 15, a pump 17, three-way valves 19,151 and 152 and an in-line heater 153 arranged in order from upstream,i.e. adjacent the outer tank 5. The three-way valve 15 is switchablebetween circulation and drain of the treating liquid. The pump 17circulates the treating liquid, and the three-way valve 19 is switchablebetween circulation of the treating liquid and removal of deionizedwater (to be described in detail hereinafter). The three-way valves 151and 152 are switchable between circulation and cooling of the treatingliquid. The in-line heater 153 heats the treating liquid circulatingthrough the supply pipe 11 to a predetermined temperature.

The three-way valves 151 and 152 have a first branch pipe 154 connectedthereto and shunted from the supply pipe 11. The first branch pipe 154has a cooling unit 155 mounted thereon. The cooling unit 155 has afunction to cool the treating liquid circulating through the firstbranch pipe 154 to a predetermined temperature.

The cooling unit 155 corresponds to the “cooling device” in thisinvention.

The supply pipe 11 has one end of an injection pipe 156 connected to aposition thereof downstream of the in-line heater 153 and upstream ofthe jet pipes 9. The other end of the injection pipe 156 is connected toa deionized water source 157. The injection pipe 156 has a control valve158, a mixing valve 159 and a flow control valve 160 arranged in orderfrom downstream to upstream. The control valve 158 controls supply andcutoff of deionized water, solvents or a treating solution of thesolvents in deionized water. The mixing valve 159 has, connectedthereto, one end of each of two chemical pipes 161 and 162, with theother ends thereof connected to an HFE source 163 and an IPA source 164,respectively. The two chemical pipes 161 and 162 have flow controlvalves 165 and 166 for adjusting flow rate, respectively. The mixingvalve 159 has a function to mix HFE (hydrofluoroether), which is awater-insoluble fluoric solvent, and/or water-soluble IPA (isopropylalcohol).

The mixing valve 159 corresponds to the “water-soluble solvent injectingdevice” and “water-insoluble solvent injecting device” in thisinvention.

The supply pipe 11 has a second branch pipe 167 connected to thethree-way valve 19 upstream of the cooling unit 155 and to the three-wayvalve 152 downstream of the cooling unit 155. The second branch pipe 167has an oil-water separation filter 168 for separating the deionizedwater and solvent in the treating liquid. The supply pipe 11 furtherincludes a third branch pipe 169 extending parallel to the second branchpipe 167. The third branch pipe 169 communicates with the second branchpipe 167 in positions upstream and downstream of the oil-waterseparation filter 168. The third branch pipe 169 has an adsorptionfilter 170 for adsorbing and removing deionized water from the treatingliquid. The adsorption filter 170 is formed of a molecular sieve,activated carbon, alumina or the like, and has a function to adsorb andremove even a trace quantity of deionized water from the treatingliquid.

The second branch pipe 167 noted above has a static mixer 171 disposedupstream of the oil-water separation filter 168. A fourth branch pipe172 communicates with the second branch pipe 167 in positions upstreamof this static mixer 171, and downstream of the static mixer 171 andupstream of the oil-water separation filter 168. The fourth branch pipe172 includes a control valve 173 for controlling circulationtherethrough. The static mixer 171 has an injection portion 174 disposedin an upstream position thereof for injecting deionized water into thetreating liquid circulating through the second branch pipe 167. A flowcontrol valve 175 is provided for controlling a flow rate of deionizedwater to the injection portion 174. As described in detail hereinafter,the static mixer 171 has no actuator, but agitates and mixes fluids byaction of division, turning and reversal.

A control valve 176 is disposed between the three-way valve 19 andsecond branch pipe 167, and a control valve 177 is mounted on the thirdbranch pipe 169. The second branch pipe 167 has a control valve 178disposed in the most upstream position thereof, and a control valve 179in the most downstream position. The third branch pipe 169 has a controlvalve 180 disposed downstream of the adsorption filter 170.

The oil-water separation filter 168 corresponds to the “separatingdevice” in this invention. The adsorption filter 170 corresponds to the“deionized water removing device” in this invention. The static mixer171 corresponds to the “mixer” in this invention.

Next, reference is made to FIG. 11 which is a view in vertical sectionshowing an outline of the static mixer 171.

The static mixer 171 includes a body portion 181 and a plurality ofelements 182 arranged in the body portion 181. Each element 182 is inthe form of a rectangular plate member twisted 180 degrees. Adjoiningelements 182 are twisted in opposite directions. The static mixer 171has the above-noted injection portion 174 disposed in the upstreamposition thereof for injecting deionized water into the treating liquid,and agitates and mixes these liquids by action of division, turning andreversal. Particularly where the solvent is water-insoluble such as HFE(hydrofluoroether) that does not dissolve completely in deionized water,the deionized water can be separated efficiently by passing the mixturethrough the oil-water separation filter 168 after mixing deionized waterand solvent in the static mixer 171.

Next, reference is made to FIG. 12 which is a view in vertical sectionshowing an outline of the oil-water separation filter 168.

The oil-water separation filter 168 includes a housing 184, a liquidintroducing portion 185 in the bottom of the housing 184, a filter 186for filtering the treating liquid from the liquid introducing portion185, a first storage portion 187 for storing part having a high specificgravity of the liquid having passed the filter 186, a second storageportion 188 for storing part having a low specific gravity, an inflowportion 189 through which the treating liquid flows into the liquidintroducing portion 185, a first discharge portion 190 for dischargingthe liquid from the first storage portion 187, a second dischargeportion 191 for discharging the liquid from the second storage portion188, and a cooling pipe 192 arranged along the outer wall of housing 184for indirectly cooling the filter 186. The inflow portion 189 is locatedupstream with respect to the second branch pipe 167, and the firstdischarge portion 190 downstream with respect to the second branch pipe167. The filter 186 is a microfiber filter having a function to trap adifferentiated free liquid and flocculate the liquid into coarse masses.The free liquid differentiated to the order of microns is flocculated tothe order of millimeters, thereby to be instantaneously distributed intoa perfect bilayer system by specific gravity difference. The efficiencyof oil-water separation can be improved by cooling the cooling filter186 with the cooling pipe 192.

The inner tank 3 has a concentration meter 193 disposed in an upperposition thereof for measuring a deionized water concentration in thetreating liquid. The concentration meter 193 may be the infraredabsorption type, for example.

A controller 194, which corresponds to the “control device” in thisinvention, performs an overall control of the apparatus including thevertical movement of the holding arm 7, operation and stopping of thepump 17, temperature control of the in-line heater 153, flow control ofthe flow control valves 160, 165, 166 and 175, opening and closing ofthe control valve 158, switching control of the three-way valves 15, 19,151 and 152, and opening and closing of the control valves 173, 176,177, 179 and 180.

The controller 194 controls the various components noted above to carryout a “deionized water cleaning process” for moving the holding arm 7 tothe treating position and supplying deionized water as treating liquid,a “replacing process” for supplying the water-soluble solvent (IPA) todeionized water to replace the deionized water with the water-solublesolvent, a “cooling process” for causing the cooling unit 155 to coolthe treating liquid, and a “separating and removing process” for causingthe oil-water separation filter 168 to remove deionized water from thetreating liquid. Subsequently, the controller 194 carries out an“adsorbing and removing process” for causing the adsorption filter 170to adsorb and remove deionized water from the treating liquid. Then, thecontroller 194 carries out a “replacement promoting process” forinjecting the water-insoluble solvent into the treating liquid toreplace the water-soluble solvent with the water-insoluble solvent. Whenthe deionized water concentration in the treating liquid falls to orbelow a predetermined value, the controller 194 carries out a “finishingprocess” for injecting a small quantity (e.g. about 5 to 10%) ofwater-soluble solvent again, and causing the adsorption filter 170 tofurther adsorb and remove deionized water from the treating liquid.However, during the “replacing process” and “separating and removingprocess”, the treating liquid is passed through the oil-water separationfilter 168 after operating the static mixer 171 to agitate and mix thedeionized water and solvent by action of division, turning and reversal,thereby improving the efficiency of separation by the oil-waterseparation filter 168. The static mixer 171 is effective particularlywhere the solvent is water-insoluble and does not easily dissolve indeionized water. After the “finishing process”, a solvent is sprayedfrom a nozzle, not shown, to form a solvent atmosphere, and the holdingarm 7 is pulled up from the treating tank 1 to dry the wafers W.

It is preferable to confirm the saturation solubility of the solvent inthe treating liquid before the “adsorbing and removing process”, but theconcentration meter 193 can be used as substitution. A specific value ofdeionized water concentration is 0.1 [%] or less, for example. When the“adsorbing and removing process” is carried out while the deionizedwater concentration is still high, the adsorption filter 170 will losewater-adsorbing power in a short time, necessitating frequent changes ofthe adsorption filter 170. It is desirable to avoid such aninconvenience.

In the “replacement promoting process”, preferably, the controller 194operates the flow control valve 165 to inject the water-insolublesolvent at a low flow rate. Then, the inner tank 3 may be filled withthe water-insoluble solvent while maintaining an interface with thewater-soluble solvent stored in the inner tank 3. This ensures anefficient replacement of the water-soluble solvent with thewater-insoluble solvent.

Next, operation of the above substrate treating apparatus will bedescribed with reference to FIG. 13. FIG. 13 is a flow chart ofoperation.

Step S21

The controller 194 switches the three-way valve 15 to a position forallowing circulation, switches the three-way valves 19, 151 and 152 topositions for communication with the supply pipe 11, opens the controlvalve 158, and adjusts the flow control valve 160 to supply deionizedwater in a predetermined flow rate from the deionized water source 157through the injection pipe 156 and supply pipe 11 to the inner tank 3.After filling all of the inner tank 3, outer tank and supply pipe 11with deionized water, the controller 194 operates the pump 17 andin-line heater 153 to heat the deionized water to a predeterminedtemperature (e.g. 60° C.). After the predetermined temperature isreached, the controller 194 lowers the holding arm 7 from the standbyposition to the treating position, and maintains the holding arm 7 inthe treating position for a predetermined time. As a result, the wafersW are cleaned with the deionized water heated to the predeterminedtemperature.

Step S22

The controller 194 stops the in-line heater 153 and pump 17, switchesthe three-way valve 15 to a drain position, and closes the flow controlvalve 160. The controller 194 adjusts the flow control valve 166 to apredetermined flow rate to supply IPA to the supply pipe 11. After theinner tank 3 and outer tank 5 are filled with IPA, the controller 194switches the three-way valve 15 to the position for communication withthe supply pipe 11, and operates the pump 17. As a result, a large partof deionized water in the treating solution is discharged, and IPA ismixed into the treating solution whereby the deionized water is replacedwith IPA.

Step S23

The controller 194 switches the three-way valves 151 and 152 topositions for communication with the first branch pipe 154, and causesthe cooling unit 155 to cool the treating liquid to a predeterminedtemperature. By cooling the treating liquid to this level, deionizedwater is rendered not easily soluble in IPA.

Step S24

The controller 194 opens the control valves 176, 178 and 179, andswitches the three-way valve 19 to a position for communication with thesecond branch pipe 167. As a result, the treating liquid passes throughthe oil-water separation filter 168 after IPA and deionized water arefully mixed by the static mixer 171.

At this time, the flow control valve 175 may be adjusted to inject asmall quantity of deionized water into the treating liquid flowingthrough the static mixer 171. A deionized water concentration in thesolvent below a certain value would lower the efficiency of theoil-water separation filter 168 separating deionized water and solvent.Deionized water is positively injected and mixed into the treatingliquid having a reduced deionized water concentration, so that theoil-water separation filter 168 may separate deionized water below thecertain value as drawn out by the injected deionized water.

After executing above process for a predetermined time, the controller194 opens the control valves 177 and 180, and closes the control valves178 and 179, to switch the channel to the fourth branch pipe 172,providing a bypass for the treating liquid to circumvent the staticmixer 171. As a result, the treating liquid with a reduced deionizedwater concentration passes only through the oil-water separation filter168. It is possible to omit the fourth branch pipe 172 so that thetreating liquid may always flow through the static mixer 171.

Step S25

The controller 194 opens the control valves 177 and 180, and closes thecontrol valves 178 and 179. As a result, the treating liquid (largelyIPA) with a reduced deionized water concentration flows into the thirdbranch pipe 169. A small quantity of deionized water remaining in thetreating liquid is adsorbed and removed by the adsorption filter 170.

Step S26

After executing above adsorbing and removing process for a predeterminedtime, the controller 194 switches the control valve 15 to the drainposition, and switches three-way valves 19, 151 and 152 to the positionsfor communication with the supply pipe 11. Further, the controller 194adjusts the flow control valve 165 to supply HFE at a low flow rate tothe inner tank 3. As a result, IPA is gradually pushed up by HFE withoutmixing therewith, to be discharged from the inner tank 3 and replaced byHFE. However, a small quantity of deionized water still remains in thetreating liquid and in the fine patterns on the wafers W. After theinner tank 3 is filled with HFE, the controller 194 closes the controlvalve 158 and flow control valve 165, switches the three-way valve 19for communication with the second branch pipe 167, opens the controlvalves 178 and 179, and closes the control valve 173. As a result, as instep S24 above, the treating liquid including HFE circulates through thestatic mixer 171 and oil water separation filter 168 to have thedeionized water removed. After a predetermined time of deionized waterremoval by the oil-water separation filter 168, the controller 194switches the channel as in step S25 for adsorption and removal by theadsorption filter 170.

Step S27

The controller 194 refers to the concentration meter 193, and performsthe adsorbing process with the adsorption filter 170 until the deionizedwater concentration in the treating liquid falls to or below apredetermined value. The predetermined value is 0.1 [%] or less, forexample.

Step S28

The controller 194 carries out a finishing process by injecting IPAagain into the treating liquid with a reduced deionized waterconcentration.

Specifically, the controller 194 opens the control valve 158, andadjusts the flow control valve 166 to inject a small quantity of IPAinto the treating liquid. Its concentration is about 5 to 10%, forexample. The adsorbing and removing action of the adsorption filter 170is maintained in this state, whereby a slight quantity of deionizedwater is removed from the treating liquid including mostly HFE and asmall quantity of IPA. As a result, the deionized water remaining alsoin the fine patterns on the wafers W can be drawn out and removed.

Step S29

After executing above process for a predetermined time, the controller194 supplies solvent vapor from the nozzle, not shown, to form a solventatmosphere around the treating tank 1. The holding arm 7 is raised tovolatilize HFE adhering to the wafers W and dry the wafers W.

According to this embodiment, as described above, the controller 194carries out the deionized water cleaning process for cleaning the wafersW in the treating tank 1 with deionized water by supplying deionizedwater from the filling pipe 156 to the supply pipe 11. This processremoves chemicals, contaminants and the like from the wafers W withdeionized water. Next, the controller 194 carries out the replacingprocess for injecting IPA through the mixing valve 159, and replacingthe deionized water with IPA. After replacing the deionized water storedin the treating tank 1 with IPA, the controller 194 carries out thecooling process by switching the channel to the first branch pipe 154for the cooling unit 155 to cool the treating liquid. Subsequently, thecontroller 194 carries out the separating and removing process byswitching the channel to the second branch pipe 167 for the oil-waterseparation filter 168 to remove deionized water from the treatingliquid. Deionized water can be removed efficiently from the treatingliquid since the treating liquid has been cooled in the cooling processto render the deionized water not readily dissolvable in IPA. Then, thereplacement promoting process is performed by injecting HFE through themixing valve 159. IPA and deionized water are replaceable nearlycompletely with HFE since IPA and deionized water are made not readilydissolvable in HFE in the preceding cooling process. Thus, the deionizedwater in the treating tank 1 can be removed efficiently to prevent thedeionized water from remaining in the fine patterns formed on the wafersW. As a result, this apparatus can prevent collapse of the fine patternsformed on the wafers W.

This invention is not limited to the foregoing embodiment, but may bemodified as follows:

(1) The foregoing embodiment provides the static mixer 171 for fullymixing the water-insoluble solvent with deionized water prior to passagethrough the oil-water separation filter 168. However, the static mixer171 is not absolutely necessary, and may be omitted. This simplifies theapparatus construction.

(2) The foregoing embodiment uses, by way of example, fluoric HFE aswater-insoluble solvent, and IPA as water-soluble solvent. Thisinvention is applicable to other solvents. It is possible to use, forexample, HFC (hydrofluorocarbon) as fluoric solvent other than HFE.

(3) The foregoing embodiment provides the concentration meter 193mounted in the inner tank 3 for measuring deionized water concentration.This construction may be modified to measure deionized waterconcentration in the treating liquid circulating through the supply pipe11.

(4) In the foregoing embodiment, the “finishing process” is performedbefore the drying process. However, the “finishing process” may beomitted where the deionized water concentration is sufficiently reducedin the “replacement promoting process”.

This invention may be embodied in other specific forms without departingfrom the spirit or essential attributes thereof and, accordingly,reference should be made to the appended claims, rather than to theforegoing specification, as indicating the scope of the invention.

1. A substrate treating apparatus for treating substrates with atreating liquid, comprising: a treating tank having an inner tank forstoring the treating liquid, and an outer tank for collecting thetreating liquid overflowing the inner tank; a supply pipeinterconnecting said inner tank and said outer tank for circulating thetreating liquid; a first branch pipe shunted from said supply pipe; aseparating device mounted on said first branch pipe for separatingdeionized water and a solvent in the treating liquid, and dischargingthe deionized water; a second branch pipe interconnecting positionsupstream and downstream of said separating device; a deionized waterremoving device mounted on said second branch pipe for adsorbing andremoving deionized water from the treating liquid; an injection pipeconnected to said supply pipe for injecting deionized water in aposition downstream of said separating device; a solvent injectingdevice for injecting the solvent into said injection pipe; and a controldevice for carrying out a deionized water cleaning process for supplyingdeionized water from said injection pipe and cleaning the substratesinside the cleaning tank with the deionized water, then a replacingprocess for injecting the solvent from said solvent injecting device andreplacing the deionized water with the solvent, a separating andremoving process for switching to said first branch pipe and causingsaid separating device to remove the deionized water from the treatingliquid, and an adsorbing and removing process for switching to saidsecond branch pipe and causing said deionized water removing device toadsorb and remove the deionized water from the treating liquid.
 2. Anapparatus as defined in claim 1, further comprising: a mixer mounted onsaid first branch pipe for mixing deionized water and solvent; and athird branch pipe interconnecting a position upstream of said mixer, anda position downstream of said mixer and upstream of said separatingdevice; wherein said control device is arranged, when the solvent iswater-soluble, to switch a flow of the treating liquid to said thirdbranch pipe to carry out the separating and removing process, and whenthe solvent is water-insoluble, to allow the treating liquid to flowthrough said mixer to carry out the separating and removing process. 3.An apparatus as defined in claim 2, wherein said mixer has an injectingportion for injecting deionized water.
 4. An apparatus as defined inclaim 1, wherein said separating device has a filter for separating oiland water, a housing enclosing said filter, an inflow portion formed insaid housing for introducing the treating liquid, an outflow portionformed in said housing for letting out the treating liquid having passedthrough said filter, a discharge portion formed in said housing fordischarging deionized water separated by said filter, and a coolingdevice for cooling said filter.
 5. An apparatus as defined in claim 2,wherein said separating device has a filter for separating oil andwater, a housing enclosing said filter, an inflow portion formed in saidhousing for introducing the treating liquid, an outflow portion formedin said housing for letting out the treating liquid having passedthrough said filter, a discharge portion formed in said housing fordischarging deionized water separated by said filter, and a coolingdevice for cooling said filter.
 6. An apparatus as defined in claim 1,further comprising: an ultrasonic applying device for applyingultrasonic vibration to the treating liquid stored in said inner tank;and a concentration meter for measuring deionized water concentration inthe treating liquid; wherein said control device is arranged to operatesaid ultrasonic applying device after the deionized water concentrationmeasured by said concentration meter falls to a predetermined value. 7.An apparatus as defined in claim 6, wherein said predetermined value is10,000 ppm.
 8. An apparatus as defined in claim 1, wherein said solventinjecting device is arranged to inject one of HFE (hydrofluoroether) andIPA (isopropyl alcohol).
 9. A substrate treating apparatus for treatingsubstrates with a treating liquid, comprising: a treating tank having aninner tank for storing the treating liquid, and an outer tank forcollecting the treating liquid overflowing the inner tank; a supply pipeinterconnecting said inner tank and said outer tank for circulating thetreating liquid; a deionized water supply device for supplying deionizedwater as treating liquid; a solvent supply device for supplying asolvent as treating liquid; a branch pipe shunted from said supply pipe;a deionized water removing device mounted on said branch pipe forremoving deionized water from the treating liquid; a solvent injectingdevice for injecting the solvent into the supply pipe downstream of saiddeionized water removing device; and a control device for carrying out adeionized water cleaning process for supplying deionized water from saiddeionized water supply device and cleaning the substrates inside thecleaning tank with the deionized water, then a replacing process forinjecting the solvent from said solvent supply device and replacing thedeionized water with the solvent, a deionized water removing process forswitching to said branch pipe and causing said deionized water removingdevice to remove the deionized water from the treating liquid, andcausing said solvent injecting device to replenish the solvent.
 10. Anapparatus as defined in claim 9, further comprising: a first mixermounted on said branch pipe upstream of said deionized water removingdevice for mixing fluids; a deionized water injecting device forinjecting deionized water into said branch pipe upstream of said firstmixer; and a second mixer mounted on said supply pipe down-stream ofsaid solvent injecting device for mixing fluids; wherein said controldevice is arranged, when deionized water concentration in the treatingliquid falls below a predetermined value, to inject deionized water fromsaid deionized water injecting device, and control said deionized waterinjecting device and said solvent injecting device such that a sum of aninjection rate of the solvent from said solvent injecting device and adifference between an injection rate of deionized water and a quantityof the treating liquid removed by said deionized water removing devicebecomes substantially zero.
 11. An apparatus as defined in claim 9,wherein said deionized water removing device has a filter for separatingoil and water, a housing enclosing said filter, an inflow portion formedin said housing for introducing the treating liquid, an outflow portionformed in said housing for letting out the treating liquid having passedthrough said filter, a discharge portion formed in said housing fordischarging deionized water separated by said filter, and a coolingdevice for cooling said filter.
 12. An apparatus as defined in claim 10,wherein said deionized water removing device has a filter for separatingoil and water, a housing enclosing said filter, an inflow portion formedin said housing for introducing the treating liquid, an outflow portionformed in said housing for letting out the treating liquid having passedthrough said filter, a discharge portion formed in said housing fordischarging deionized water separated by said filter, and a coolingdevice for cooling said filter.
 13. An apparatus as defined in claim 9,wherein said deionized water removing device comprises a deionized wateradsorbing and removing device for adsorbing deionized water whilepassing the solvent.
 14. An apparatus as defined in claim 9, whereinsaid solvent supply device is arranged to supply HFE (hydrofluoroether),and said solvent injecting device is arranged to inject IPA (isopropylalcohol).
 15. A substrate treating apparatus for treating substrateswith a treating liquid, comprising: a treating tank for storing thetreating liquid; a supply pipe for circulating the treating liquid tosupply the treating liquid discharged from the treating tank back to thetreating tank; a first branch pipe shunted from said supply pipe; acooling device mounted on said first branch pipe for cooling thetreating liquid flowing therethrough; a second branch pipeinterconnecting positions of the supply pipe upstream and downstream ofsaid cooling device; a separating device mounted on said second branchpipe for separating deionized water and a solvent in the treatingliquid, and discharging the deionized water from the treating liquid; aninjection pipe connected to said supply pipe for injecting deionizedwater in a position downstream of said separating device; awater-soluble solvent injecting device for injecting a water-solublesolvent into said injection pipe; a water-insoluble solvent injectingdevice for injecting a water-insoluble solvent into said injection pipe;and a control device for carrying out a deionized water cleaning processfor cleaning the substrates inside the cleaning tank with deionizedwater, then a replacing process for injecting the water-soluble solventfrom said water-soluble solvent injecting device into said supply pipeand replacing the deionized water with the water-soluble solvent, acooling process by switching a channel to said first branch pipe forsaid cooling device to cool the treating liquid, a separating andremoving process by switching a channel to said second branch pipe forsaid separating device to remove the deionized water from the treatingliquid, and a replacement promoting process for injecting thewater-insoluble solvent from said water-insoluble solvent injectingdevice into said supply pipe.
 16. An apparatus as defined in claim 15,further comprising: a third branch pipe interconnecting positionsupstream and downstream of said separating device; and a deionized waterremoving device mounted on said third branch pipe for adsorbing andremoving the deionized water from the treating liquid; wherein saidcontrol device is arranged to switch the channel to said third branchpipe after said separating and removing process.
 17. An apparatus asdefined in claim 16, further comprising: a mixer mounted on said secondbranch pipe upstream of said separating device for mixing deionizedwater and the solvent; and a fourth branch pipe interconnecting aposition upstream of said mixer, and a position downstream of said mixerand upstream of said separating device; wherein said control device isarranged to switch the channel to said mixer for said separating andremoving process and said replacement promoting process, and switch thechannel to said fourth branch pipe for other processes than saidseparating and removing process and said replacement promoting process.18. An apparatus as defined in claim 15, wherein said water-solublesolvent injecting device is arranged to inject IPA (isopropyl alcohol)as the water-soluble solvent.
 19. An apparatus as defined in claim 15,wherein said water-insoluble solvent injecting device is arranged toinject HFE (hydrofluoroether) as the water-insoluble solvent.
 20. Anapparatus as defined in claim 15, wherein said control device isarranged to inject the water-insoluble solvent at a low flow rate fromsaid water-insoluble solvent injecting device.